JP4610534B2 - Friction stir welding joint for joined member and method for manufacturing joined structure - Google Patents

Description

The present invention relates to a friction stir welding in which a rotating agitation shaft is inserted into a joined portion where the members to be joined are abutted, and is softened by frictional heat to agitate and join, and in particular, the joined portion is formed on a joined member on a curved surface portion. The present invention also relates to a friction stir joint and a method for manufacturing a joined structure formed by joining the members to be joined.

  In recent years, various friction stir welding methods have been proposed as new joining methods that replace metal welding and brazing. FIG. 4 is a diagram showing an outline of such a friction stir welding method. As shown in the figure, the friction stir welding is performed by abutting the joining surfaces of a pair of flat plates 101 and 102 as members to be joined, and being harder than the plates 101 and 102 along the joining line 200 where the joined portions are continuous. A friction stir welding tool 110 having a material stirring shaft (probe) 112 is inserted while rotating at high speed. Then, a pair of plates 101 and 102 are agitated and joined while being plastically fluidized by frictional heat and pressure generated at the joining portion.

By the way, such friction stir welding is not only applied to a flat plate as shown in FIG. 4 but also to a structure constituted by joining members to be joined having curved surfaces, such as a railway vehicle structure. It is desired. FIG. 3 is a diagram showing a conventional joining method for friction stir welding between members to be joined whose joining end surfaces form curved surfaces, and shows before joining (a), during joining (b), and after joining (c). ing.
In the friction stir welding, the probe 112 of the friction stir welding tool 110 is inserted into the joint portion 210 where the joining end faces of the members 103 and 104 to be joined are rotated. At this time, it is necessary to prevent the material from flowing due to the shoulder 113 on the lower surface of the rotating body 111 holding down the plastic flowing material. Therefore, in order to press down the joint surface of the members to be joined 103 and 104 with the entire shoulder 113, as shown in FIG. 3 (b), the members to be joined 103 and 104 are agitated.
JP 7-505090 Gazette

  However, the bonded members 103 and 104 that have been friction stir welded have their joints scraped by the rotating body 111 to form a flat surface 221 along the bonding line on the product surface 220 or to the bonded member. When the insertion of 111 becomes deep, a groove is formed. Therefore, for a structure obtained by friction stir welding of a member to be joined having a curved surface portion, after the joining, a flat surface 221 and a groove are putty so that the product surface 220 is flush with the post-treatment to prepare the surface. It was necessary. For example, in the case of a railway vehicle structure, since a long distance of 20 to 25 meters is joined, post-processing requires a large amount of putty. And there is a concern that the putty used for the post-processing is likely to cause paint cracking due to deterioration over time or deformation of the vehicle structure due to a load applied to the vehicle body during use. Therefore, there is a problem that such a bonded structure requiring post-processing is costly due to subsequent maintenance.

Accordingly, the present invention provides a friction stir welding joint for a member to be joined for friction stir welding of curved surfaces and a method for manufacturing a joined structure including the member to be joined having the joint in order to solve such a problem. The purpose is to do.

In the joint for friction stir welding of a member to be welded according to the present invention, the joint end surface of the member to be welded is a curved surface portion, and a friction stir welding tool probe is inserted into the joint portion where the joint end surfaces are butted together. for performing bonding, which has been formed on the workpieces, wherein the joint end portion of the joint member, the protruding portion having a planar working surface which is perpendicular to the joining end surface is formed, said machining The height of the surface is substantially the same as the product surface after the protrusion is deleted at the position of the joint end surface, and the height increases as the distance from the joint end surface increases .

Further, in the method for manufacturing a bonded structure according to the present invention, the bonded end surfaces of the members to be bonded are curved surfaces, and the probe of the friction stir welding tool is inserted into the bonded portion where the bonded end surfaces are abutted to each other. a method of manufacturing a joined structure formed by joining, a protruding portion of the joint end portion having a flat processing surface perpendicular to the joining end face, remove the projections that processed surface at the position of the joining end face The joined members are formed so as to substantially coincide with the product surface after being subjected to the friction , and the joining end surfaces are brought into contact with each other so that the shoulder of the friction stir welding tool is pressed against the processing surface of the protrusion. Stir welding is performed, and then the protrusion is removed so that the product surface is flush.

  Therefore, according to the present invention, since the surface finish is performed by cutting after the friction stir welding, it is not necessary to fill the putty or the like, so that the maintenance work at the joint portion of the joint structure is not required as in the prior art. In addition, since the protrusion is a small protrusion in which the processed surface and the product surface substantially coincide with each other at the position of the joining end face, it can be easily cut without preparing a large-scale cutting device in the processing after joining. It became possible.

Next, an embodiment of a method for manufacturing a joint for friction stir welding of a member to be joined and a joint structure according to the present invention will be described with reference to the drawings.
Conventionally, as shown in FIG. 3, when the joining members 103 and 104 having curved surfaces are joined to each other by joining portions 210 that join the joining end surfaces, the entire shoulder 113 of the friction stir welding tool 110 is made of material. Therefore, the rotating body 111 has scraped the surface of the member. Therefore, as shown in FIG. 1, first, as shown in FIG. 1, protrusions are provided on the members to be joined in advance, and the surface of the joining portion is flattened so that the shoulder 113 of the friction stir welding tool 110 and the whole contact with the same depth. It is possible. FIG. 1 is a view showing a joining method using a joint for friction stir welding of a member to be joined having protrusions on the surface of the joined portion, showing before joining (a), during joining (b), and after joining (c). ing.

  The to-be-joined members 51 and 52 have a curved product surface 56 at their joining end portions, and the joining end surfaces 51a and 52a are flat so as to face each other. Then, a projection 53 is formed on the product end 56 side of the curved surface portion at the joining end, and as shown in FIG. 1A, a single plane (processed) with the joined members 51 and 52 butted together. Surface) 54. The processing surface 54 is formed so as to be a plane orthogonal to the rotation axis of the friction stir welding tool 110, and at the time of joining in which the joining end faces 51a and 52a of the members to be joined 51 and 52 are brought into contact with each other, A protrusion having a certain width is formed in the longitudinal direction (direction passing through the drawing). Then, the probe 112 of the friction stir welding tool 110 is inserted into the joint portion 55 where the joint end faces 51a and 52a are abutted while rotating at high speed.

  At the time of joining, the probe 112 of the friction stir welding tool 110 penetrates deeper than the product surface 56 beyond the protrusion 53 as shown in FIG. Then, the shoulder 113 is pressed against the processing surface 54 on the upper surface of the protrusion 53. Friction heat is generated at the joint portions 55 of the members to be joined 51 and 52 by the stirring of the probe 112, and further, the material is agitated while being plastically fluidized by the pressure at which the probe 112 moves, and the members to be joined 51 and 52 abutted against each other. Are joined. And after a joining structure is comprised by the friction stir welding of to-be-joined members 51 and 52, the cutting process for removing the protrusion 53 is performed as post-processing. That is, as shown in FIG. 1C, the protruding portion 53 indicated by the broken line is removed, and the product surfaces 56 of the members to be joined 51 and 52 are finished so as to be continuously flush with each other.

  In this way, the protrusion 53 is provided in joining the members to be joined 51 and 52 having curved surfaces, and surface finishing is performed by cutting after the friction stir welding, so that the member to be joined 51 is not filled with putty as in the conventional case. 52, the product surface 56 of the joined structure can be made flush with the base material as it is. This eliminates the problem of paint cracking due to aging and load due to use, such as putty, and eliminates the need for maintenance work on the joint in the conventional joint structure.

  As for the friction stir welding joint, as shown in FIG. 1, a projecting portion is provided at the joining end portion. Conventionally, friction stir welding between flat workpieces has been proposed. For example, it is described in Japanese Patent No. 3014654. However, this is a configuration for compensating for the volume that is lost when the material in which the projecting portion of the joining portion is plastically flowed downward by the friction stir welding tool 110 during joining. In this respect, the protrusion 53 shown in FIG. 1 described above is for forming a plane on which the shoulder 113 of the friction stir welding tool 110 contacts, and when the thickness of the joint is sufficient, the material flows out. Is not a problem.

  However, the protrusion 53 is finally cut, and if the protrusion 53 is simply provided on the curved surface, it is necessary to determine the agitation depth by the probe 112 in consideration of the amount to be cut in post-processing. . This is because if the depth of the stirring portion 57 is shallow, sufficient bonding strength cannot be obtained. If the length of the probe 112 is increased, the width of the material that plastically flows is increased, so that the diameter of the shoulder 113 must be increased. Therefore, the protrusion 53 formed with the processing surface 54 so as to hit the shoulder 113 is configured with the width of the processing surface 54 being about 1.5 times the shoulder diameter, and thus the protrusion 53 becomes large. In order to cut the protrusion 53, a large-scale dedicated facility is prepared, which causes a problem that the manufacturing cost increases.

  Therefore, the friction stir welding joint for a member to be joined according to the present invention is configured in consideration of these points, and specifically, as shown in FIG. Drawing 2 is a figure showing the joining method by the joint for friction stir welding of an embodiment, and shows before joining (a), during joining (b), and after joining (c). The to-be-joined members 1 and 2 of this embodiment shown in FIG. 2 have a curved product surface 6 at the joining end, and the joining end surfaces 1a and 2a are formed with flat surfaces so as to face each other. . And the protrusion part 3 is formed in the joining edge part on the surface side which makes a curved surface. The processing surface 4 is formed so that the upper surface of the protrusion 3 is a plane orthogonal to the rotation axis of the friction stir welding tool 110. Therefore, as shown in FIG. 1A, when the joining end faces 1a and 2a of the members 1 and 2 to be joined are brought into contact with each other, protrusions having a constant left and right width are formed in the longitudinal direction (direction passing through the drawing).

  And the protrusion part 3 of this embodiment has the height of the processing surface 4 substantially coincided with the product surface 6 (part indicated by a broken line) at the position of the joining end faces 1a and 2a, and the height increases as the distance from the joining end face increases. The length h is increased. In other words, the protrusion 3 has a height h from the product surface 6 to the processed surface 4 after the deletion is zero at the positions of the joint end faces 1a and 2a, and gradually increases in a direction away from the joint end face. Yes. The height h of the step with respect to the product surface 6 formed at the end of the protrusion 3 depends on the radius of curvature at the R portion of the members 1 and 2 to be joined and the shoulder diameter of the friction stir welding tool 110. For example, in the case of a railway vehicle structure, when the curvature radius of the shoulder is 400 mm, it is approximately 0.2 mm.

  Therefore, when joining the members 1 and 2 to be joined, as shown in FIG. 2B, the probe 112 of the friction stir welding tool 110 is inserted into the joint 5 while rotating at high speed, and the joint 5 Move along a continuous joining line (in a direction through the drawing). At this time, the shoulder 113 is pressed against the processing surface 4 on the upper surface of the protrusion 3. Friction heat is generated in the joint portion 5 of the members to be joined 1 and 2 by stirring of the probe 112, and the material is agitated while being plastically fluidized by the pressure at which the probe 112 moves, and the members to be joined 1 and 2 that are abutted against each other. Are joined. Then, after the friction stir welding of the members 1 and 2 is performed, a cutting process for removing the protrusions 3 is performed as post-processing. That is, as shown in FIG. 2 (c), the protruding portion 3 indicated by the broken line is removed, and the product surface 6 of the joined structure composed of the members 1 and 2 to be joined is finished so as to be a continuous curved surface. .

  Therefore, in the case of the present embodiment, by performing surface finishing by cutting after friction stir welding, the product surface 6 of the joined structure can be obtained by using the base material of the members 1 and 2 as they are without filling the putty as in the prior art. Can now be leveled. Therefore, the joined structure formed by joining the members 1 and 2 is free from problems such as paint cracking due to deterioration due to aging such as putty and load due to use, and maintenance work caused by conventional joining is not necessary. It was.

Further, since the thickness of the protrusion 3 is substantially zero at the positions of the joint end faces 1a and 2a, the cutting of the protrusion 3 does not scrape off the friction stirrer 7 that the probe 112 has frictionally stirred. It can be left as it is . Therefore, since the depth at which the probe 112 is inserted becomes the depth of the friction stir welding portion as it is, the length dimension of the probe 112 in consideration of post-cutting processing, as shown in FIG. Accordingly, it is not necessary to increase the diameter of the shoulder 113, and as a result, the protrusion 3 can be reduced. This makes it possible to easily perform cutting with a grinder or the like without preparing a large-scale cutting device in post-processing.

As mentioned above, although one embodiment was described about the manufacturing method of the joint for friction stir welding of a member to be joined, and the manufacturing method of a joined structure, the present invention is not limited to this but can be variously changed in the range which does not deviate from the meaning. is there.

It is the figure which showed the joining method by the joint for friction stir welding of the to-be-joined member which provided the processus | protrusion on the surface of a junction part, (a) before joining (b) and after joining (c) are shown. It is the figure which showed the joining method by the joint for friction stir welding of embodiment, and has shown before joining (a), joining (b), and after joining (c). It is the figure which showed the conventional joining method about the friction stir welding of the to-be-joined members in which a joining end surface makes a curved surface part, and has shown before joining (a), joining (b), and after joining (c). It is a figure which shows the outline | summary of the friction stir welding method.

Explanation of symbols

1, 2 to-be-joined member 3 projection part 4 processing surface 5 joining part 6 product surface 1a, 2a joining end face 110 friction stir welding tool 111 rotating body 112 probe 113 shoulder

Claims (2)

Friction formed on the member to be joined for performing friction stir welding by inserting the probe of the friction stir welding tool into the joint part where the joint end surfaces of the members to be joined are in the curved surface part In the stir welding joint,
A protrusion having a flat processing surface orthogonal to the bonding end surface is formed at the bonding end of the member to be bonded, and the height of the processing surface is after the protrusion is deleted at the position of the bonding end surface. The joint for friction stir welding of a member to be welded is characterized in that it substantially coincides with the product surface and increases in height as the distance from the joining end surface increases . In the manufacturing method of the bonded structure in which the bonded end surfaces of the members to be bonded are in the curved surface portion, and the probe of the friction stir welding tool is inserted into the bonded portion where the bonded end surfaces are butted together to bond the members to be bonded together.
A projection of a joint end having a flat processed surface orthogonal to the joint end surface, the processed surface being substantially coincident with the product surface after the projection is deleted at the position of the joint end surface. Forming a member to be joined,
Perform friction stir welding so as to pressing the shoulder of the friction stir welding tool against the working surface of the projection portion abutting to each other the joining end face,
Then, the production method of the joining structure, wherein the product surface to remove the protrusions so as to flush.

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